Uranium-238 (atomic number 92) undergoes alpha decay. What is the daughter nuclide?
Answer and explanation
Correct answer: C. Thorium-234, atomic number 90
- Step 1: An alpha particle is a helium-4 nucleus: mass number falls by 4 and atomic number falls by 2. Step 2. . Answer: Thorium-234, atomic number 90. Why not the others: mass number must fall by 4; protactinium-234 is the beta daughter of thorium-234; radium-234 would need a larger drop in atomic number.
Practise more Nuclear and astrophysics.
Free questions with an explanation for every one, and full timed A-Level UK (AQA, Edexcel, OCR) mock tests.
More Nuclear and astrophysics questions
- A radioactive source has a half-life of 8.0 hours and an initial activity of 800 Bq. What is the activity after 24 hours?
- Carbon-14 has a half-life of 5730 years. What is its decay constant?
- Helium-4 has a mass defect of 0.0304 u. (1 u = 931.5 MeV) What is its binding energy per nucleon?
- A small gamma source gives 400 counts per minute at 1.0 m. Ignoring background and absorption, what is the rate at 2.0 m?
- Hubble's constant is 70 km/s/Mpc. What is the recession speed of a galaxy 300 Mpc away?
- The hydrogen line at 656.3 nm in the laboratory is observed at 660.0 nm in a galaxy. What is its recession speed? (c = 3.00 x 10^5 km/s)